If there is only a heater involved you could get a 240V/110V transformer and wire a mains cable to the 240V side, then the 110V to the appliance.
But make sure it is rated to the current power.
And do not forget the earth needs to be connected.

If it has "heater plates" which are wired in parallel, then maybe you could rewire them in series (assuming that there are 2 or 4 or 6 of them). Otherwise perhaps you could just put a great big diode in series with the power line, so the device would only get half-wave power.